1. Field of the Invention
The present invention relates generally to the field of electronic apparatus, more particularly to the field of electronic switched-output controller apparatus, and still more particularly to electronic, multiple switched-output, such as switched-power and/or switched-signal, controller apparatus.
2. Background Discussion
Industry often utilizes unattended and/or remotely-located power equipment which is required to be turned on and off in accordance with a preestablished schedule or in response to certain external conditions or stimuli. For example, switched-output power controllers are frequently used to power-up and power-down electrical or electronic equipment, and switched-output control apparatus may be used for providing low-voltage or signal inputs to electronic equipment requiring such inputs for operation.
As an example of switched power needs, when a number of current-drawing electronic apparatus, such as computers, disc drives and printers, are connected to a common building electrical outlet, turning on all the apparatus at the same time can result in a combined high start-up current spike. Such a turn-on power spike may be sufficiently high to trip the circuit breaker associated with the building electrical outlet supplying power to the apparatus, even though the combined steady-state current requirements of all the apparatus are within the current capacity of the circuit. Without time-delay sequencing of the turning on of the equipment, there is needed either a higher current capacity building circuit or more than one building outlet circuit--neither of which may be available or practical to provide in already-constructed offices or buildings.
An appropriately configured, switched-output power controller which provides time-delay turn-ons for the various pieces of connected electronic equipment, so that they do not all turn on at the same instant, can typically remedy this problem of high cumulative start-up current spikes without requiring special or multiple building circuits.
On the other hand, even if the available building circuit capacity is capable of handling high start-up current spikes caused by the simultaneous turning on of a number of pieces of electrical or electronic equipment, it may be required or desired to turn on certain pieces of the equipment before others are turned on. For example, it may be required to turn on a stand-alone disc drive so that it is "up and running" before the associated computer is turned on. Similar delayed turn-off of several pieces of some electronic or electrical equipment may be needed.
Other situations requiring the controlled turning on and off of electrical power or operating signals to electronic or electrical equipment are unattended installations of such equipment or location of such equipment in remote or relatively-inaccessible places. It may, for example, be desired to turn off unattended computers or computer systems whenever they are idle for a predetermined length of time and to turn them back on when they are addressed. It may also be desired to turn off certain unattended or remote electronic equipment, such as computers, fans, or pumps, when monitored ambient conditions, such as temperature, pressure and/or humidity exceed or fall below predetermined limits and to turn the equipment back on when the ambient conditions return to acceptable values.
By way of a still further example, it may be necessary, for equipment protection, to turn off certain pieces of equipment when the available line voltage exceeds or falls below safe equipment operating limits and to turn the equipment back on when the line voltage returns to within predetermined limits.
Controllers having switched power and/or switched signal outputs for the remote controlling of equipment such as motors, pumps, electrical heaters, computers and printers are known. U.S. Pat. No. 5,450,334 (the "'334 patent") to Pulizzi et al., which is incorporated in its entirety herein by reference, discloses, for example, a one time programmable controller apparatus having a number of switched outputs for providing power, operating signals or "dry" contacts to equipment that is connected to the controller apparatus.
The operating sequence of the switched outputs, as disclosed in the '334 patent, is controlled by a one time programmable microprocessor which is programmed, by a burning-in process, by the manufacturer, thereby enabling low-volume, custom switched-output controller apparatus using common components.
Multiple time delay power controllers such as are, for example, disclosed in U.S. Pat. No. 4,769,555 to Pequet, et al., are useful for switched power controlling situations. However, they and other switched-output controllers tend to be uneconomical when only one or a few of the switched-output controllers of a particular configuration are required by customers. The principal reason for this is because such switched-output controllers have heretofore, so far as is known to the present inventors, required to be constructed using customized, "hard wired" circuit cards or boards to which are mounted individual electronic components or circuits.
As another example, U.S. Pat. No. 4,918,562 (the '562 patent) to Pulizzi et al., which is also incorporated herein in its entirety by reference, discloses a more universal--and generally more costly--switched-output controller apparatus which is controlled by a software programmable microprocessor or microcontroller which enables purchasers of the apparatus to program the apparatus to their individual requirements and to reprogram the apparatus as the requirements change.
The power controller apparatus disclosed in the '334, '555 and '562 patents also include conventional RS232 input/output connections which enable remote operation, through modems, from a conventional telephone line.
The switched-output controller apparatus disclosed and claimed in the '334, '555 and '562 patents are extremely useful, especially in the operation of a single group of remotely-controlled electrical apparatus. However, those disclosed switched-output controller apparatus, and other similar, known apparatus, have certain deficiencies when two or more switched-output controller apparatus are needed to control two or more spaced-apart groups of electrical equipment. This is particularly the situation when operation of all the switched-output controller apparatus and their respective groups of electrical equipment is desired or required to be remotely operated in a particular manner or sequence by a single master control and the switched-output controller apparatus are required to be located remotely from one another.
As an example, consider that remote first, second and third switched-output controller apparatus, each having RS232 connections and each having a unique electronic identification number or "address", are used to control respective first, second and third groups of electrical or electronic equipment in accordance with electronic instructions from a single master controller. One possible manner of operating the three switched-output controller apparatus by the master control is for the master control to provide addressed instructions to the first switched-output controller apparatus over a telephone line.
A modem at the master control and another at the first switched-output controller apparatus are connected to provide digitally encoded instructions to the RS232 input of first switched-output controller apparatus. The RS232 output of the first switched-output controller apparatus is connected to the RS232 input connection of the second switched-output controller apparatus and the RS232 output thereof is connected to the RS232 input connection of the third switched-output controller apparatus.
Addressed instructions from the master control are received by the first switched-output controller apparatus and passed on by the RS232 connection to the second switched-output controller apparatus and then, in the same way, onto the third switched-output controller apparatus so that all three switched-output controller apparatus receive the instructions from the master control at virtually the same instant. The switched-output controller apparatus to which the instructions are addressed acts upon the instructions (e.g., to operate the switched outputs) while the instructions are ignored by the other switched-output controller apparatus to which the instructions are not addressed.
A significant limitation of such an arrangement as described above is that the RS232 connections of each of the switched-output controller apparatus are capable of relaying instructions to the next-in-sequence switched-output controller apparatus over a distance of only about two hundred feet. This is not a problem if each switched-output controller apparatus is not separated from the next previous and next following switched-output control apparatus by a distance of over about two hundred feet. It is, however a problem if the distance between any two adjacent switched-output controller apparatus exceeds two hundred feet--as may be the situation when, for example, the controller apparatus are widely spaced apart in large industrial complexes or in installations such as crude oil or gas pipeline installations or widely scattered drilling sites in an oil field.
In such situations where the switched-output controllers are required to be spaced more than two hundred feet apart, it has heretofore, to the knowledge of the present inventors, been the uneconomical practice for the master control to communicate with each of the switched-output controller apparatus by separate telephone lines with each of the controller apparatus having to have its own dedicated modem. Such use of a number of separate telephone lines and modems to communicate with widely spaced apart switched-output controller apparatus requires costly installation and maintenance.
It is, therefore, a principal objective of the present invention to provide switched-output controller apparatus which are able to relay digitally-encoded instructions from one such controller apparatus to another over distances to four thousand feet for the controlling of widely separated groups of electrical or electronic equipment, as is often needed in large industrial complexes, crude oil and gas pipelines, oil fields, highway monitoring systems, university complexes, agricultural applications and similar installations.